diff --git a/modules/swagger-codegen/src/main/resources/php/api.mustache b/modules/swagger-codegen/src/main/resources/php/api.mustache
index f039a6baa17..61874746b39 100644
--- a/modules/swagger-codegen/src/main/resources/php/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/api.mustache
@@ -150,7 +150,7 @@ use \{{invokerPackage}}\ObjectSerializer;
         {{/minimum}}
         {{#pattern}}
         if ({{^required}}!is_null(${{paramName}}) && {{/required}}!preg_match("{{{pattern}}}", ${{paramName}})) {
-            throw new \InvalidArgumentException('invalid value for "{{paramName}}" when calling {{classname}}.{{operationId}}, must conform to the pattern {{{pattern}}}.');
+            throw new \InvalidArgumentException("invalid value for \"{{paramName}}\" when calling {{classname}}.{{operationId}}, must conform to the pattern {{{pattern}}}.");
         }
         {{/pattern}}
 
diff --git a/modules/swagger-codegen/src/main/resources/php/model_generic.mustache b/modules/swagger-codegen/src/main/resources/php/model_generic.mustache
index e66d4247430..8286a9b9f4d 100644
--- a/modules/swagger-codegen/src/main/resources/php/model_generic.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/model_generic.mustache
@@ -271,7 +271,7 @@ class {{classname}} {{#parentSchema}}extends {{{parent}}} {{/parentSchema}}imple
         {{/minimum}}
         {{#pattern}}
         if (!preg_match("{{{pattern}}}", ${{name}})) {
-            throw new \InvalidArgumentException('invalid value for ${{name}} when calling {{classname}}.{{operationId}}, must be conform to the pattern {{{pattern}}}.');
+            throw new \InvalidArgumentException("invalid value for ${{name}} when calling {{classname}}.{{operationId}}, must conform to the pattern {{{pattern}}}.");
         }
         {{/pattern}}
         {{/hasValidation}}
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
index 3635aebefe8..ccc4a5019fe 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
@@ -261,7 +261,7 @@ class FakeApi
             throw new \InvalidArgumentException('Missing the required parameter $pattern_without_delimiter when calling testEndpointParameters');
         }
         if (!preg_match("/^[A-Z].*_/", $pattern_without_delimiter)) {
-            throw new \InvalidArgumentException('invalid value for "pattern_without_delimiter" when calling FakeApi.testEndpointParameters, must conform to the pattern /^[A-Z].*_/.');
+            throw new \InvalidArgumentException("invalid value for \"pattern_without_delimiter\" when calling FakeApi.testEndpointParameters, must conform to the pattern /^[A-Z].*_/.");
         }
 
         // verify the required parameter 'byte' is set
@@ -287,7 +287,7 @@ class FakeApi
         }
 
         if (!is_null($string) && !preg_match("/[a-z]/i", $string)) {
-            throw new \InvalidArgumentException('invalid value for "string" when calling FakeApi.testEndpointParameters, must conform to the pattern /[a-z]/i.');
+            throw new \InvalidArgumentException("invalid value for \"string\" when calling FakeApi.testEndpointParameters, must conform to the pattern /[a-z]/i.");
         }
 
         if (!is_null($password) && (strlen($password) > 64)) {
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
index e61c0f33ce1..819f3a5013d 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
@@ -509,7 +509,7 @@ class FormatTest implements ArrayAccess
     {
 
         if (!preg_match("/[a-z]/i", $string)) {
-            throw new \InvalidArgumentException('invalid value for $string when calling FormatTest., must be conform to the pattern /[a-z]/i.');
+            throw new \InvalidArgumentException("invalid value for $string when calling FormatTest., must conform to the pattern /[a-z]/i.");
         }
         $this->container['string'] = $string;